There should be a market. LGBTQ+ youth want representation in media.

Don't think about their sexuality when you write them. Real-life LGBTQ+ struggles won't apply in your fantasy setting. It's easy to just say "in my world people aren't jerks" and everyone's cool with it, but challenge yourself to create new challenges for them to overcome. They'll feel more like real characters that way. And every relationship has struggles, not just same-sex couples.

Sometimes the LGBTQ+ community isn't the right ones to ask. I recently discovered that one of my main characters is gay. And I'm a straight guy writing a gay guy. It kind of helps that my wife writes yaoi, and she writes it well, so I've read some of her stuff for inspiration. But I'm not trying to write smut. Anyway, the community won't appreciate the fact that my young gay hero becomes a villain. Having a gay villain without a good gay character is bad representation, and you can't have that, but he's not bad because he's gay, he's bad because he wants to prevent what happened to his little sister from happening to anyone else. He's got a point until he starts killing people. What he does and the choices he makes aren't because of the fact that he's attracted to men. And he isn't attracted to the hero who kills him. I think it's gonna be fine. I guess what I'm trying to say is, don't romanticize, vilify, or otherwise make an LGBTQ+ character any more special than a cishet one.